1. Field of the Invention
The present invention relates to an artificial biomembrane, especially to an artificial biomembrane for simulating natural biomembranes. The present invention also relates to a method for manufacturing such an artificial biomembrane. These artificial biomembranes are used for ecological restorations and treatments of water environment in pollution.
2. Description of the Related Art
Natural biomembranes in water environment can decompose pollutant and purify water. The results of researches indicate that biomembranes contain thousands and tens of thousands of different kinds of microbes, such as bacteria, fungi, algae, protozoan and the like. They adhere to various substrate surfaces in water environment, and excretive viscous materials are embed to be a structure composed of cells, substrates, interstices, flow channels.
In the filed of sewage treatment, there are activated sludge process and biomembranes process. Microbes are hard core of purification. Natural biological membranes are used in biomembranes process, in which microbes adhere to surfaces of certain carriers in national conditions. There are advantages as follows for this method,                1) no problems of sludge bulking and expedient operation and management;        2) better endurance of changes of sewage quality and quantity;        3) less quantity of residual sludge, reduction of processing cost of sludge and better quality of discharged water.        
How can we artificially simulate natural biomembrane and apply? This belongs to the field of immobilized microbe research, that is to immobilize microbial cells of suspended growth on carriers by microbiology and technology to improve processing load and purification efficiency of new enhanced biological treatment technology.
There are a variety of microbial cell immobilization technologies, such as adsorption immobilization, self-immobilization, embedding immobilization and crosslinking immobilization etc. Embedding immobilization is a technology of microbial immobilization on widely research, which can embed and immobilize efficient microbial cells by film-forming polymers to form kindred biomembrane structure for water environment treatment. The advantages are as follows: high concentrations of microbes; in favor of immobilization of dominant Bacteria and improvement of purification efficiency; less yield of sludge; good solid-liquid separation; good resistant capacity of impulse load. However, the technology is still in the laboratory stage in the field of sewage treatment in China. “The technology of immobilized cells sewage treatment is still in the laboratory stage” is cited from “Organic Industrial Wastewater Treatment Theory and Technology” wrote by Jian Yang and the like, Chemical Industry Press 2005. There still exists problems below:                1) complex preparation of immobilized particles, weak mechanical strength, short life;        2) large diffusion resistance, mass transfer capacity to be improved;        3) easy adhesion and float of immobilized particles;        4) large-scale production equipment and technology to be developed.        
In order to make immobilized microbial particles, the embedded materials and processes should meet the following requirements:                1) simple process of immobilization and easy large-scale production;        2) low cost;        3) non-deleterious to microbial cells;        4) high density of immobilized cells and joint action of a variety of microbes;        5) good permeability and mass transfer capacity of substrate;        6) good chemical stability and high physical strength;        7) antimicrobial decomposition and long life.        
The requirements cited above which the embedded materials and processes should meet are cited from “biological immobilization technology and water pollution control” wrote by Jian-long Wang, the Science Press 2002.
The traditional method of cell immobilization is piercing method, in which the film-forming material containing microbial cells is immobilized by dripping into liquid fixative. For example, sodium alginate is immobilized in CaCl2 solution; polyvinyl alcohol is immobilized in boric acid solution. The process is complex, with long immobilizing and washing time and low preparation efficiency, and difficult to large-scale production.
Microencapsulation is a technology using natural or synthetic polymer materials to embed solid, liquid, even liquid substances to form micro-particles with semipermeable or sealed membrane. The technology solves many technological problems that could not solved by means of traditional technology. The content above is cited from “Food Microcapsule and Ultramicro Pulverization Processing Technology” wrote by Jun Zhang and the like, chemical Industry Press 2004. The technology can be applied to production of artificial biomembranes after amelioration.
So far, the search has not found a published artificial biomembrane for treatment of water environment in pollution and the preparation method.